Have some pics in your ideabooks to help you communicate with the contractor. Look at the work that the contractor has done in the past. Ask questions like: were there any problems (there always is at least one)? If so, how did they get solved? Was he/she accessible for questions/concerns? Did he/she clean up every night? Show up every day? Did he/she use subs, if so, how did that go? Was he/she on time and within budget? If not, why? Did he/she pull the permits and get them signed off punctually? Bid the job, look carefully at each bid, they will all be different. Most expensive and least expensive does not mean much, ask to have the bid explained if you don't understand it. Take your time to find the right person to work with you.
Hiring or consulting a designer would be the best path if you are already stuck on just finding a contractor. The contractor is there for demo, remodel and install purposes -- not design, functionality and consultation about what you'd like to get out of the space, much less spec'ing and ordering everything.
Dytecture